Self-luminous instrument



April 6, .1937. J. E. PAUL 2,075,864

SELF LUMINOUS INSTRUMENT Filed March 23; 1935 |NVENTOR ,1 BY M ZM,DM, 11M$M 11/5 ATTORNEYS Patented Apr. 5, i937 UNITED STATES PATENT OFFlQE SELF-LUMINOUS INSTRUMENT Application March 23, 1935, Serial No. 12,746

12 Claims.

This invention relates to self-luminous instruments and more particularly, concerns instruments having figures, scales or other indicia or parts illuminated by self-luminous radio-active 5 material so as to be visible in the dark.

Many types of indicating instruments have been made self-luminous by coating the indices, pointers, hands or like elements thereof with self-luminous paint. Paint of this type is composed of finely divided radio-active material dispersed in a suitable fluid adhesive or binder. The adhesives used, which are usually lacquer derivatives and oils, become discolored, either as the result of exposure to sunlight, because of the action of the radium compounds thereon, or from other causes. The discolored adhesive surrounds the particles of self-luminous radium compound and masks or absorbs the light given ofi thereby with the result that the luminous intensity of the paint is reduced to an objectionable extent.

Another undesirable feature of self-luminous paint arises from the fact that it is impossible to apply this material to a uniform depth over the entire area of the small instrument elements or indicia which are to be illuminated, the paint layer invariably being much thinner at the edge of the painted element than near the center thereof with a resultant non-uniformity of luminous intensity. The field of use of self-luminous paint for illuminating indicia is limited to instruments or like apparatus having comparatively large dials with large and fairly widely spaced indicia thereon. Many instrument dials, such as the dials of portable or aircraft carried signaling or radio communicating apparatus, are necessarily of limited size, and self-luminous paint is entirely unsuited to such applications. The amount of selfluminous paint that can be applied to small dial *0 lines and figures is frequently insuilicient to produce the required brightness, or, if a suitably visible luminous intensity is obtained, a halo effect is produced which blurs the lines and figures to such an extent that they are indistinguishable.

With the above and other considerations in mind, it is proposed in accordance with the present invention to provide an improved type of self-luminous element for instruments, in which the self-luminous material is employed Without he use of deteriorating and discoloring adhesives or other binders and in which the self-luminous material is employed in such a manner that it produces clear, bright and sharply defined instrument indicia which are readily legible and distinguishable in the dark regardless of small size and close spacing. A further object or" the invention is the provision of self-luminous instru' ments or instrument parts in which the selfluininous material is very economically employed while at the same time, a high degree of luminous intensity is obtained.

In general, the above and other objects of my invention are carried out by employing dry, finely divided radio-active material, unmixed with adhesives or other foreign matter and densely packing this material in small fiat containers having at least one transparent wall of considerable area. The packed container is disposed beneath the dial or indicating surface of an instrument with the transparent Wall uppermost, and the desired marks or indicia are formed by opaque means on the dial surface which clearly define the markings against the luminous background of the self-luminous material. Thus, for example, the opaque indicia defining means may comprise opaque letters, numerals or other distinctive marks carried on a transparent plate or surface disposed over the self-luminous material container, the opaque markings being clearly defined against the self-luminous background. In another embodiment, the indicia defining means takes the form of a stencil having apertures therethrough shaped in the form of letters, numerals, or other marks required, so that the portions of the self-luminous material Visible through the stencil apertures appear as clearly defined and brilliant self-luminous indicia.

Both the stencil and the transparency type of opaque indicia defining means may be applied toeither stationary dial instruments having movmg hands or pointers, moving dial instruments with stationary pointers or moving dial instruments in which a limited area only of the dial visible. In one embodiment of my invention, opaque indicia defining means is carried by a moving dial covered by an opaque shield or plate having a sight opening therethrough. In this embodiment, the self-luminous screen or container is considerably smaller than the dial area to be illuminated, being of a size sufli'cient to 4 illuminate that portion of the dial which is aligned with the sight opening in the dial shield. This embodiment of the invention eiiects a considerable saving in the amount of self-luminous material required Without sacrificing the brilliance or legibility of the dial indicia.

In many cases, I prefer to removably secure the transparent container of self-luminous material beneath the instrument dial or surface so that this container may be readily refilled or re- 0 placed after the self-luminous material therein has deteriorated beyond. its useful brilliance.

Referring to the drawing, in which certain embodiments of the invention have been illustrated:

Figure 1 is an elevation of an instrument dial of the stationary type embodying one modification of my invention;

Figure 2 is a sectional view taken along the line 22 of Figure 1;

Figure 3 is an elevation similar to Figure 1 showing another modification of my invention applied to a stationary dial instrument;

Figure 4 is an elevation of a movable dial instrument embodying my invention;

Figure 5 is a sectional View taken along the line 55 of Figure 4;

Figure 6 is an elevation of a different type of movable dial for use in the instrument of Figures 4 and 5;

Figure 7 is an elevation of a movable dial instrument with a sight aperture embodying my invention; and

Figure 8 is a sectional view taken along the line 88 of Figure 7.

The embodiment of my invention shown in Figures 1 and 2 comprises a stationary dial instrument in which the indicia are defined by an opaque stencil. A relatively fiat self-luminous screen S is provided beneath the instrument dial or surface it. This screen may take various forms, and as shown, may comprise a pair of closely spaced parallel plates or sheets l0 and H, at least one of which, namely the upper plate iii, is formed of transparent material such as glass. The plates id and ii are spaced apart by a gasket 53 extending around the peripheries thereof and secured to the plates by cement or otherwise. An edge-protecting frame or binding 14 is preferably provided, and has flanges overlying the outer surfaces of the plates 10 and H adjacent their edges as shown.

The space between the plates l0 and H defined by the gasket 53 is filled with a densely compacted mass of dry powdered self-luminous material l5, which customarily includes a radium compound. This material may be introduced to the space between the parallel plates through an opening in the gasket l3 or otherwise, and is preferably compacted to a dense, homogeneous and non-shifting mass by the rapid vibration of the container or in any other suitable manner. The compacting method employed may comprise that disclosed in detail in my copending applications, Serial Nos. 730,705 and 730,705, filed June 15, 1934. After the introduction of the self-luminous material, the air may be suitably exhausted from the screen container and the filling opening thereof is closed and preferably sealed.

The self-luminous screen S is relatively thin or flat and has an area considerably larger than the area occupied by the indicia on the instrument dial which it illuminates. The chamber for the self-luminous material l5 between the plates in and ii may be of any desired thickness, and in general, is of suflicient thickness to produce the desired luminous intensity by the use of self-luminous material of comparatively low specific luminous intensity whereby the life of the screen is prolonged.

The self-luminous screen S is suitably secured to or adjacent the rear face of the instrument dial i2 behind the portion of the dial on which the illuminated indicia are to appear. The

screen S may be connected to or adjacent'the plate I?! by soldering, cementing, clamping or otherwise, and this connection is preferably such that the screen may be removed for refilling or replacement without damage to the dial or the screen. This removable connection between the screen S and the dial i2 has been illustrated in Figure 1 by a soldered or cemented joint at the point 37.

In the particular instrument illustrated in Figures 1 and 2, the indicia comprise figures on an arcuate scale and the screen S is accordingly of arcuate form and of appreciably greater width and arcuate length than the scale figures. The scale figures are formed by cutting stencil apertures IE through the opaque dial plate 12 over the screen S, these apertures outlining the figures, letters or other indicia required on the dial. With this arrangement, the' portions of the self-luminous screen S exposed through the apertures i6 form brightly illuminated and sharply defined indicia having a uniform luminous intensity at all points.

The instrument of Figures 1 and 2 is provided with the usual movable pointer I? carried by a shaft EB and the pointer may be illuminated by applying self-luminous paint thereto or by mounting a transparent container of self-lu minous material thereon. In the disclosed embodiment, the pointer l? is coated with a layer ll of self-luminous paint.

In a modified form of the invention, the required dial indicia are defined against the illuminated background of a self-luminous screen by means of opaque markings on a transparent dial surface rather than by apertures in an opaque dial surface. Thus, as shown in Figure 3, the dial plate $9 of the instrument, or at least the portion thereof overlying the self-luminous screen S, is formed of celluloid, glass or any other suitable transparent material so that the light from the screen passes through the dial. The required dial markings or indicia, such as the figures 2|, are formed of any suitable light impervious material such as dark paint, metal foil, sheet metal or the like, and may be painted on or cemented to the under or rearward surface of the transparent dial section 20, in order to protect the indicia from dislodgement.

The self-luminous screen S is preferably of the same construction as the screen S of the instrument shown in Figures 1 and 2, and may be similarly removably secured to or adjacent the rearward face of the dial E9. The pointer 22 of the instrument shown in Figure 3 may be coated with self-luminous paint or may carry a transparent container of self-luminous material, if desired. However, in some cases, it is preferred to merely form the pointer 22 of opaque material and to extend the free end thereof over the inner edge of the exposed self-luminous screen S. This arrangement has been shown in the drawing, where pointer tip 23 is clearly visible in the dark since it is silhouetted against the luminous background formed by the screen S shining through the transparent dial section 20.

The stencil and the transparency modifications of my invention may be applied to various dial arrangements other than the fixed dial and movable pointer devices of Figures 1 through 3. Thus, for example, either the stencil or the transparency arrangements may be applied to movable dial instruments, and such modifications have been shown in Figures 4, 5, and 6.

As shown in Figures 4 and 5, the instrument dial may comprise a circular, opaque disc 24 suitably mounted on a central shaft 25 or otherwise to rotate within a stationary annular rim or plate 26. Suitable stencil apertures 21 are formed in the disc 24 of a shape to define in outline the required figures, letters or other indicia. A self-luminous screen C of the type described above in connection with Figures 1, 2, and 3, is disposed below and close to the movable dial disc 24, and in overlapping relation to the stencil apertures 21. As shown in the drawing, the screen C may be removably fixed to the rearward or under face of the dial 24, if desired, or the screen may be separately mounted on a stationary support with its outer surface close to the under surface of the disc 24. The self-luminous screen C is preferably of annular form as shown, extending completely about the dial disc 25. An index mark 28 is provided on the stationary annular rim 23, and this mark may be illuminated by forming it of self-luminous paint.

The indicia of the movable dial instrument of Figures 4 and 5 may be illuminated by opaque markings on a transparent member. A movable dial construction of this nature is shown in Figure 6, wherein a dial plate 23 of suitable transparent material is disposed over or secured 30 to the face of a self-luminous screen C. The

screen C is of annular form and may be identical with the screen C of the instrument shown in Figures 4 and 5. The required indicia 30 are formed of opaque paint or other suitable material fixed to the under surface of the transparent dial plate 29. These indicia are clearly defined against the luminous background of the screen 0 as explained above in connection with the stationary dial instrument of Figure 3. The dial 40 of Figure 6 may be rotatably supported within a stationary rim in the manner explained in connection with Figures 4 and 5 and the screen C may be removably connected to rotate with the dial or may be stationary as desired.

45 In another embodiment of the invention, I prefer to employ a moving dial and to expose and illuminate only a limited portion thereof, thereby effecting a considerable economy in the amount of self-luminous material employed.

5 Thus as shown in Figures 7 and 8, the instrument dial 3| may comprise a transparent disc having opaque markings 32 thereon which are of a shape to define the required figures, letters, or other indicia. The dial disc 3| is rotatably 55 supported on a shaft 33 in the usual manner. A stationary shield or instrument face plate 34 is disposed over the dial disc 3| and a sight aperture 35 is formed in the shield, preferably at the top of the instrument face as shown in 60 Figure 7. The aperture 35 is large enough to expose a limited section of the marked transparent dial disc 3|, and a lubber line or marker 38 extends across the center of the aperture 35, as shown. A stationary self-luminous screen D 65 of the type heretofore described is suitably supported beneath the movable dial disc 3| adjacent its edge. The screen D is slightly larger than the sight aperture 35, and is disposed directly beneath this aperture, as shown in Figure '7. As the dial disc 3| turns, the opaque markings 32 on different parts of the dial disc 3| are brought between the self-luminous screen D and the sight aperture 35, and these markings define the dial indicia against the self-luminous 75 background of the screen D. With the arrangement described, the dial disc 3|, which may carry a scale of considerable arcuate extent is brilliantly illuminated at the point where readings are desired by the use of a comparatively small amount of self-luminous material, since the selfluminous screen need extend only over a fraction of the total scale area of the dial.

It will be apparent that instead of employing opaque markings on the transparent dial disc 3| of Figures '7 and 8, this disc may be formed of opaque material with the required indicia formed thereon by stencil apertures.

My invention makes possible the clear and distinguishable illumination of figures, letters and other dial indicia of far smaller size and closer spacing than the smallest legible illuminated indicia previously known. The increased legibility is due in part to the absence of obscuring or light absorbing binders for the self-luminous material, and also to the fact that my improved arrangement of the self-luminous material prevents the emanation of light laterally from the figures or other illuminated areas, and thus prevents the blurring of the indicia by so-called halo effects. In general, by the use of myinvention, an observer can read and distinguish in darkness, printing, lettering or other marks of the same size and spacing as the smallest and most closely spaced indicia that he can read and distinguish by daylight.

I claim:

1. In a self-luminous instrument, in combination, a dial plate, a self-luminous screen comprising a fiat container filled with self-luminous material and having a transparent wall disposed adjacent the under surface of said dial plate, said dial plate including contrasting opaque and transparent means over and aligned with said transparent wall of said screen and shaped to define dial indicia against the luminous background of said screen, indicating means, and means for permitting relative movement between said indicating means and said indicia defining means.

2. In a self-luminous instrument, in combiner tion, an opaque dial plate having a plurality of stencil apertures therethrough shaped to form dial indicia, a screen comprising a fiat transparent container filled with self-luminous material removably secured to the under surface of said dial plate and covering said stencil apertures, luminous indicating means, and means for permitting relative movement between said indicating means and said dial plate apertures.

3. In a self-luminous instrument, in combination, a transparent dial plate, a self-luminous screen comprising a flat transparent container filled with self-luminous material removably secured to the under surface of said dial plate, a plurality of opaque markings on the under surface of said dial plate over said self-luminous screen forming visible dial indicia against the luminous background of said screen and indicating means movable relative to said opaque markings.

4. In a self-luminous instrument, in combination, a transparent dial plate, a self-luminous screen comprising a fiat transparent container filled with self-luminous material removably secured to the under surface of said dial plate, a plurality of opaque markings on the under surface of said dial plate over said self-luminous screen forming visible dial indicia against the luminous background of said screen and a pointer movable over the outer surface of said dial plate and extending over at least'a part of said selfluminous screen.

5. In a self-luminous instrument, in combination, a dial plate having a transparent section, a self-luminous screen removably secured to the under surface of said dial plate and covering said transparent section and a plurality of opaque markings on said transparent section shaped to form dial indicia against the luminous background of said screen.

6. In a self-luminous instrument, in combination, a dial plate having a transparent section, a self lurninous screen removably secured to the under surface of said dial plate and covering said transparent section, a plurality of opaque markings on the under surface of said transparent section over said screen shaped to define dial indicia against the luminous background of said screen, and a movable pointer above said dial plate having a portion thereof overlying said transparent dial section whereby a portion of said pointer is silhouetted against the luminous background of said screen.

7. In a self-luminous instrument, in combination, a movable dial plate, a stationary shield over said dial plate having a sight opening therethrough, a stationary self-luminous screen beheath said dial plate and aligned with said sight opening in said shield and opaque means on said dial plate shaped to define dial indicia visible through said sight opening against the luminous background of said screen.

8. In a self-luminous instrument, in combina tion, a movable dial plate, a stationary shield over said dial plate having a sight opening therethrough, a stationary self-luminous screen comprising a fiat container filled with self-luminous material and having a transparent wall disposed adjacent the under surface of said dial plate and substantially aligned with said sight opening, and opaque means on said dial plate disposed to move into alignment with said sight opening in said shield and shaped to define dial indicia against the luminous background of said screen.

9. In a self-luminous instrument, in combination, a dial plate, contrasted opeque and light transmitting means on said dial plate defining indicia arranged in a scale of considerable area thereon, a self-luminous screen beneath said scale of said dial plate and having a considerably smaller area than said scale and means for causing relative movement between said dial plate and said screen whereby different portions of said scale may be successively disposed over said screen.

10. In a self-luminous instrument, in combination, a dial plate having a transparent scale area thereon, opaque means on the transparent scale area of said dial plate forming dial indicia, a container of self-luminous material having a transparent Wall of smaller area than said scale area of said dial plate disposed beneath and adjacent a portion of said scale area, and means for causing relative movement between said dial plate and said container whereby different portions of said scale area are illuminated by the self-luminous material in said container.

ll. In a self-luminous instrument, in combination, a movable dial plate, contrasting opaque and light transmitting means on said dial plate forming a scale of dial indicia thereon, a stationary shield over said dial plate having a sight opening therethrough of smaller area than said dial plate scale, said sight opening being aligned with a portion of said scale, and a stationary self-luminous screen isposed below and adjacent said dial plate and substantially aligned and coextensive with said sight opening in said shield, whereby portions of said scale visible through said sight opening are illuminated against the luminous background of said screen.

12. In a self-luminous instrument, in combination, a movable dial plate having a transparent scale area, a stationary shield over said dial plate and having a sight opening therethrough aligned with and exposing a limited portion of the transparent scale area of said dial plate, a plurality of opaque indicia forming means on the transparent scale area of said dial plate and a stationary selfluminous screen disposed beneath and adjacent said dial plate and aligned with a portion of the scale area thereof, said self -luminous screen being smaller than said scale area and being substantially aligned with said sight opening in said shield.

JOHN E. PAUL. 

